1. Field
The present disclosure relates generally to wireless communications, and more specifically but not exclusively to various electronic circuitry or algorithms for interference management in a wireless network.
2. Background
Wireless networks are widely deployed to provide various services to consumers, such as telephony, data, video, audio, messaging, broadcasts, etc. Wireless networks enable broadband communications over a regional, nationwide, or even global region. Such networks are sometimes referred as Wireless Wide Area Networks (WWANs). One common example of a WWAN is a cellular network that supports CDMA2000, a telecommunications standard that uses Code Division Multiple Access (CDMA) to send voice, data, and signaling between mobile subscribers. Another example of a WWAN is a cellular network that provides broadband Internet access to mobile subscribers, such as Evolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB), both of which are part of the CDMA2000 family of air interface standards. Other examples include WCDMA, HSPA, LTE (Long Term Evolution) and LTE-Advanced. These cellular networks generally provide coverage over multiple cellular regions, with a fixed-site base station located in each cell to serve mobile subscribers.
In one particular exemplary use in a network, a terminal may communicate with a serving base station on the forward and/or reverse link. On the forward link, the terminal may observe high interference from an interfering base station. On the reverse link, the serving base station may observe high interference from an interfering terminal. The interference on each link may degrade performance of data transmission sent on that link. In future revisions of wireless standards such as LTE, there is a need to support base stations of different powers (e.g., high-powered macrocells and lower-powered picocells). Additionally, there may be some cells (henceforth referred to as femtocells) that operate under “restricted association,” or Closed Subscriber Group (CSG) i.e., they only allow some user terminals (UEs) to connect to them. For example, these UEs may belong to users who subscribe to a special access plan offered by the operator.
In a traditional homogeneous deployment, an UE typically connects to the cell with the highest geometry (i.e., signal to noise ratio). However, in some cases such as disjoint links, it could connect to a weaker cell as the strongest forward link geometry cell may not be the same as the strongest reverse link cell (or vice versa). Moreover, in a heterogeneous deployment, there are benefits in allowing the UE to connect to a weaker base station. For example, an UE may connect to the cell with the lowest path loss to minimize interference caused to the network, even though its geometry is lower. Similarly, in the case of restricted association, an UE may be forced to connect to a weaker geometry base station as it may not have permission to access the strongest geometry base station.